Nortel Networks 1000BASE-LX, 1000BASE-SX manual Base unit, Initial installation, Stack MAC address

50 Chapter 2 Network configuration

Base unit

The base unit is the unique stack unit that you configure with the Unit Select switch on the front panel. One BayStack 420 Switch in the stack must be configured as the base unit; all other units in the stack must have their Unit Select switch set to Off (see “Unit select switch” on page 49). You can assign any single BayStack 420 Switch as the base unit.

The physical ordering of all of the other units in the stack is determined by the position of the base unit within the stack. This is important for network management applications that view the physical ordering of the units within the stack.

Some characteristics of the base unit are described in the following sections.

Initial installation

During the initial installation of the stack, the software automatically determines the physical order of all units in the stack according to the position of the base unit within the stack. Thereafter, the individual units maintain their original unit numbering, even if you change the position of one or more units in the stack (you can renumber the units using the Renumber Stack Units screen; see “Renumber Stack Units screen” on page 154).

For example, when you initially power up the stack, the base unit becomes unit 1 and the unit that the base unit connects to becomes unit 2 (and the next unit is unit 3 and so on), until the maximum stack configuration (up to 8 units) is reached. If you change the base unit to another unit in the stack, the new base unit keeps its original unit number in the stack.

Stack MAC address

When the switch is participating in a stack configuration, a stack MAC address is automatically assigned during the stack initialization. The base unit’s MAC address, with a software offset, is used for the stack MAC address.

For example, if the base unit’s MAC address is 00-00-82-99-44-00, and the stack software offset is 1F, then the stack MAC address becomes:

00-00-82-99-44-1F

209418-A